Cooling of internal-combustion engines



June 12, 1934. M. GREEN COOLING OF INTERNAL COMBUSTION ENGINES FiledFeb. 10. 1932 PatentedjJune 12. 1934 COOLING or mrramn-conmusrron enemasFrederick Michael Green, Coventry, England, as- I signor to ArmstrongSiddeley Motors Limited,

Coventry, England Application February 10, 1932, Serial No. 592,200 InGreat Britain February 27, 1931 3 Claim.

This invention relates to the cooling of aircraft intemal-combustionengines where cooling air is directed along a passage with an adjustableinlet on to the cylinders of the engine, pref-.

5 erably by means involving the use of a streamline cowling, andparticularly to the cooling of tractor-type aircraft.

At the present time the cooling is usually arranged to give the bestresults, as regards an aeroplane, when the same is climbing. Inconsequence, there is slight under-cooling when the aeroplane is runningon the ground prior to taking off-though this is relativelyunimportant-and a slightly greater over-cooling effect at normal airspeeds. This over-cooling at normal air speeds may not be deleterious tothe running of the engine, but unnecessary drag is introduced by whichthe speed of the aeroplane is reduced.- Furthermore, in some conditions,20 there is material over-cooling which may impair the subsequentrurming of the engine, as, for example, when diving from a great heightwith the engine shut off.

It is the object of the present invention to provide an improvedair-cooling arrangement by which the above disadvantages will beobviated to a greater or less extent; and td this end the inventionbroadly consists in various im- Y provements specifically set forth inthe accom- 30 panying claims and the nature of which is hereinafterdescribed with reference to the accompanying drawing.

In a preferred arrangement according to the invention, the adjustableinlet portion of the cooling-air passage is of streamline bore for allits difierent-sized openings, and it is adapted to open outwardly (i.e., away from the propeller axis) so as to collect air at a greaterradius when a greater cooling effect is desired, such air hav- 0 ing "agreater velocity than that passing the propeller nearer its axis.

In the accompany g drawing,

Figure 1 is a perspective view of part of a streamline cowling adaptedin accordance with the invention,

Figure 2 is a vertical section of the cowling and inlet passage theretomore or less diagrammatic, with the engine in elevation, and

Figure 3 is a diagrammatic horizontal section, to a smaller scale thanthe foregoing, through that part of the cowling around the enginecylinders showing the direction of air flow.

Inthe construction shown an air-cooled aeroplane engine 2 with a bank ofindividual cylinders .3, 3 which are arranged in line is enclosed withina substantially streamline cowling 4 with a raised or channel portion,5for the accommodation of the upper part of the cylinder bank, the raisedportion being oflzset laterally from ,the bank to one side more than tothe other, as

shown in Figure 3. The air inlet 6 is provided at the forward end ofthis raised portion so as to direct air partly against the forwardcylinder and mainly down one side of the cylinder bank.

A transverse bailie 7 at the rear end of the cylinder bank causes theair which enters the inlet to be forced laterally between the cylindersto the other side of the bank, where a further baflle constituted by aside 8 of the channel portion 5 directs the air rearwardly to an outletopening 9.

In accordance with the invention, a hinged shutter 10 operable by meansof the rod 13 provides the roof or outer wall of the inlet, the undersurface 11 of the shutter and the upper surface 12 of the bottom orinner wall of the inlet being convex or substantially Venturi-shaped (inlongitudinal section) to provide a more or less streamline air flowthrough the inlet. The ar-' rangement is preferably such that for normalair 30 speeds the outer surface of the shutter will conform to thestreamline shape of the raised channel.

The Venturi inlet acts efficiently to convert the velocity of the airinto pressure which builds up 5 on the appropriate side of the cylinderbank, so that air is forced between the cylinders. When diving from aheight, or at other times, when desired, the shutter 10 can be furtheror entirely closed without introducing any material additional drag.When a greater cooling effect is required, as when climbing, the shuttercan be opened materially to increase the sectional area of .the inlet,and in this position the throat is still substantially Venturi-shaped(in longitudinal section) so that the increase of drag occasioned by thelarger inlet opening is relatively. small. When opened in this way theair collected from the slip stream is taken from a greater radius, sothat a given cross-section of inlet is more efiiciently used.

It will be evident that when applying the invention to an engine with anumber of banks of cylinders radially arranged around a commoncrankshaft, separate and similarly-spaced cooling passages, each withits own adjustable inlet portion, are preferably provided for each bank.

It will be seen that by means of the invention it is possible to ensurethat theengine shall be correctly cooled at all speeds with a minimumvariation in the drag introduced by the air-cooling arrangements.

What I claim as my invention and desire to secure by Letters Patent ofthe United States 1s:

1.. The combination with' an air-cooled internal-combustion engine, of acooling-air passage therefor, said passage having an inlet a portion ofwhich is angularly adjustable and which is substantially Venturi-shapedfor all its diflerentsized openings.

2. The combination with an internal-combustion engine having a number ofcylinders in line, of a streamlined cowling adapted to direct air

